. . .All of this matters because if Liu passes the graduate level Harvard course she is taking for free through edX—one of the leading providers of massive open online courses, or MOOCs—she will be granted 7.5 credit hours, which her school district has agreed to accept as a form of professional development that can help her earn a higher salary. Liu might be among the first students nationwide to turn free online coursework into tangible college credit, but that number may soon grow exponentially. . .